A. Field of the Invention
The present invention generally relates to a memory feature accessible without the need for any buttons (i.e., buttonless memory) used in an electronic measurement device for analyzing a sample. More particularly, the present invention relates to a buttonless memory system for retrieving, displaying and storing measurement results obtained by the electronic measurement device that is characterized as a personal and portable measurement device.
B. Description of the Background Art
Today, electronic instruments are more compact, more reliable and more user friendly than older electrical instruments. Present electronic instruments accurately perform a multitude of functions and are portable due to their compactness. These portable electronic instruments are carried by the user or conveniently kept at the user's home or office. Compactness, reliability and ease of use are especially important features for a portable electrical instrument that performs medical measurements, such as a blood/glucose meter.
Diabetics use blood/glucose meters to monitor the sugar level in their blood. Diabetics carry these compact and portable blood/glucose meters to periodically and conveniently monitor their blood/sugar level. Several types of portable blood/glucose meters exist.
Reflectance photometers determine the sugar level of a blood sample through color development. The user places a drop of blood onto a chemically treated test strip. The test strip changes color depending on the sugar concentration of the blood. The user then inserts the test strip into the reflectance photometer, and light from a light-emitting diode is reflected onto the colored test strip. Reflected light normally passes through a wavelength filter and strikes a photodetector. The electrical signals from the photodetector are evaluated and the sugar concentration of the blood sample is determined and displayed by the reflectance photometer. Some reflectance photometers also include memory for storing previous measurement results, but the memory feature is dependent upon human direction. As such, the memory feature is not always used effectively. The memory feature is important because many users, such as diabetics, must keep track of their measurement results.
These users, however, must affirmatively perform the additional function of retrieving stored measurement results from memory. In a typical reflectance photometer, the user must repeatedly press a button in order to review previous measurement results stored in memory. Unfortunately, many users have difficulty in reviewing previous measurement results stored in memory because they are intimidated by electronic instruments. In addition, the likelihood of human error degrading measurement results increases as the responsibility on the user increases. Therefore, simplicity is an important characteristic for a portable electrical measurement device for analyzing personal samples.
Another known blood/glucose meter operates using an electrode sensor technology. The user inserts a test sensor into a test slot, activating the meter. Upon activation, this blood/glucose meter using electrode sensor technology displays a calibration code and the last test result. The blood/glucose meter automatically stores the last measurement result and does not allow the user to decide whether to store a measurement result or not because this portable electrode sensor lacks memory management capability.
This blood/glucose meter continues the above display until a sample is detected at a test end of the test sensor. In use, the test end of the test sensor contacts a drop of a blood sample and, through capillary action, draws a small amount of blood into a test sensor reaction chamber housing a reagent-covered electrode. Glucose in the sample reacts with reagents on the electrode of the test sensor, and the reaction produces a current which is proportional to the glucose in the blood sample. The blood/glucose meter derives the glucose concentration from this reaction current and, after 60 seconds, displays the glucose concentration of the blood sample. Removing the test sensor deactivates the blood/glucose meter and the final measurement result is automatically stored.
This portable blood/glucose meter is simple because it automatically stores the last measurement result, but the effectiveness of this memory capability is questionable due to the lack of memory management capabilities. The last test result can simply be a control test result. The control test result is important to ascertain the accuracy of the meter but does not represent the user's actual blood/glucose level. Additionally, previous measurement devices such as the reflectance photometers described above possess memory management capabilities but require additional affirmative acts from the user such as pressing a button or switch at the right time or pressing and holding a button in order to accurately retrieve and store measurement results. The more actions the user must perform, the more likely human error can adversely affect the storing and monitoring of measurement results. Thus, it is advantageous to make blood/glucose meters or any other portable electrical measurement devices with memory management capabilities as simple as possible by not requiring the user to affirmatively perform the functions of storing and retrieving measurement results from memory.